Bacterial artificial chromosome (BAC) clones are used in a wide range of projects from genome sequencing to gene discovery. Our laboratory is identifying and assembling a set of mapped human BAC clones. This resource is available for investigators who wish to use them. The BAC clones in our resource are anchored to sequence tagged site (STS) markers in radiation hybrid maps. The mapping information of the clones is freely available on our web-based database, GenMapDB. As we mapped clones to add to this resource, it became clear that the value of this collection would be greatly increased if we could further characterize the clones and ensure that the genomic location assigned to each clone is correct. In this application, we propose to achieve these goals by accomplishing the following aims. 1. To prepare DNA on all the mapped clones for further analysis including fluorescent in situ hybridization (FISH) carried out by our collaborators and our own further characterization (Aim 2). 2. To further characterize the clones by performing HindIII fingerprinting and end sequencing. 3. To upgrade the current database and to assess the accuracy of our RH-based BAC map with data from FISH analysis. The additional information about the clones will provide a genomic reagent that can be used in projects such as mapping of chromosomal mutations, gene mapping and polymorphism screening. In the process of characterizing the clones, we will also get information that gives us insight into the concordance rate between RH map, genome sequence map and cytogenetic map.